Multiple devices on one transport

[Kevin Herron]

Is it possible to have multiple LocalDevice instances (each with their own device number) share the same transport?

Or am I stuck with one LocalDevice per available local IP address to bind to, essentially?

[terrypacker]

I have some example code for using 2 transports with 2 local devices bound to the same port. Would that solve your problem or do you need 1 transport? At the time I wrote the example I did not consider sharing the transport between devices.

/**
 * Copyright (C) 2018  Infinite Automation Software. All rights reserved.
 */
package com.infiniteautomation.bacnet4j.npdu.ip;

import java.net.InterfaceAddress;
import java.util.List;

import org.junit.Assume;
import org.junit.Test;

import com.serotonin.bacnet4j.LocalDevice;
import com.serotonin.bacnet4j.npdu.ip.IpNetwork;
import com.serotonin.bacnet4j.npdu.ip.IpNetworkBuilder;
import com.serotonin.bacnet4j.transport.DefaultTransport;
import com.serotonin.bacnet4j.transport.Transport;

/**
 * @author Terry Packer
 *
 */
public class MulltipleLocalDevices {
    
    
    @Test
    public void testMultipleLocalDevices() throws Exception {
        
        List<InterfaceAddress> usable = BacnetIpUtils.listUsableBACnetInterfaces();
        Assume.assumeTrue(usable.size() > 0);
        
        InterfaceAddress address = usable.get(0);
        String bindAddress = address.getAddress().toString().split("/")[1];
        String broadcastAddress = address.getBroadcast().toString().split("/")[1];
        
        //Configure the first network, ensure we set reuse address
        IpNetwork networkOne = new IpNetworkBuilder()
                .withLocalBindAddress(bindAddress)
                .withBroadcast(broadcastAddress, address.getNetworkPrefixLength())
                .withLocalNetworkNumber(1).withPort(9000).withReuseAddress(true).build();
        Transport transportOne = new DefaultTransport(networkOne);
        LocalDevice localDeviceOne = new LocalDevice(1, transportOne);
        
        
        
        IpNetwork networkTwo = new IpNetworkBuilder()
                .withLocalBindAddress(bindAddress)
                .withBroadcast(broadcastAddress, address.getNetworkPrefixLength())
                .withLocalNetworkNumber(1).withPort(9000).withReuseAddress(true).build();
        Transport transportTwo = new DefaultTransport(networkTwo);
        LocalDevice localDeviceTwo = new LocalDevice(2, transportTwo);
        
        localDeviceOne.initialize();
        localDeviceTwo.initialize();
        
    }

}

[Kevin Herron]

@terrypacker Yes, I think that's what I need. Thank you.

Now I need to decide if I should share one LocalDevice among the many different connections* my application might have or if each connection should have its own LocalDevice instance.

If you've got any insight to share that would be welcome.

• well, "connections", being UDP and all... but let's say configured remote device instances.

[terrypacker]

@Kevin-Herron I think that will depend on your network topology. Inside Mango we share a local device across many BACnet data sources. But we also all creating many local devices in case you want to use them in different data sources.

[Kevin Herron]

@terrypacker said in Multiple devices on one transport:

But we also all creating many local devices in case you want to use them in different data sources.

I'm not sure what you meant here.

If it helps, I really only need a LocalDevice at all because that seems to be what's required by the library for communicating with RemoteDevices. I will be not be populating the shared or multiple LocalDevices with additional objects.

My original plan was to have one LocalDevice per network adapter that might be used. For most systems this would mean just one LocalDevice.

Is there any reason to have multiple LocalDevices (which I assume requires its own device number each) if I'm not going to be actually exposing any objects?

I'm essentially only interested in reading from or writing to other BACnet devices on the network.